The Lebanese army has pledged its resolve to continue battling terrorist hours after a suicide bomber killed three of its soldiers at a checkpoint in the eastern border area of Aqabet al-Jurd near the town of Arsal.

"The army knows that it is now more than ever targeted by terrorists who want to prevent the establishment of the authority of the state and its attempts to eliminate discord," the military said in a statement issued late on Saturday.

The army command "will continue to fight and pursue terrorists, and is determined to implement the security plan... whatever the sacrifices", the statement added.

The terror bombing took place just before a new security plan came into effect on Sunday aimed at quelling spillover violence from the conflict in Syria.

Lebanon's north and east have seen clashes between those who support the rebellion against Syria's President Bashar al-Assad and those who back Damascus.

The three soldiers were killed when a bomber detonated his vehicle late on Saturday at the check point in Arsal region near the Syrian border, which hosts tens of thousands of Syrian refugees.

The deadly attack was claimed on Twitter by a shadowy group calling itself Liwa Ahrar al-Sunna -- Arabic for the Brigades of the free Sunni Muslims -- which also vowed more attacks.

"The next few days will see several jihadist and blessed attacks like this one. This is only the beginning," the group claimed, adding that the army would be among its next targets.

It further said the attack was to avenge the death of Sami al-Atrash, a Takfiri terrorist wanted in connection with car bombings targeting Lebanon's resistance movement Hezbollah.

Atrash was killed on Thursday in a shootout in Arsal with Lebanese army soldiers.